Subject N

Kazami's little sister who was confined in LABO under the designation "Subject N".
After getting caught in the 2021 Rokumei Municipal Apartment Complex Gas Explosion, she was transported to the hospital. After receiving treatment and undergoing examinations, medical staff became aware of the fact that she was a Rank S Aptitude/Ability Level 6 Communicator, and had confined her in LABO with the official story that she died of a brain hemorrhage.
After she was trained by Koki Sumida, the commissioner in charge of her, she used Senses Sympathy to change his impression of her and get him on her side in a plot to escape which tragically failed. LABO labeled her deed as the "Subject N escape incident" and renewed security measures, allowing her no chance of escape. She felt the malice LABO bared towards her, which exacerbated her own malice. The repeated experiments eventually caused her the complete loss of self, leaving nothing but a "shell" of her former self, a mass of pure malice no different from the N-ified Alice Enflamme.
It is said that when a Communicator uses Senses Sympathy, they leave traces of themselves in the memories they view in order to differentiate between those memories and reality. In each segment of memory falsified by Subject N, Natushiko sensed the scent of rosemary. That scent was the heartbreaking evidence that she was once the girl called Nagisa Tachibana.